[zeromq-dev] ZMQ Message Size Limitations

[Pieter Hintjens]

Well, yes, running in a debugging and getting a real stack dump
instead of "Killed" is useful. Considering the theoretical causes of a
crash is somewhat like examining the head of a pin for angels.

If you look at s_send() you will see it copies the memory, so the
following free is hardly likely to be a problem.

In any case if you're working in C I recommend you rapidly learn and
use CZMQ, it will save you time.

-Pieter

On Fri, Apr 11, 2014 at 6:34 PM, Mark Hotchkiss
<mark.hotchkiss at yahoo.com> wrote:
> But I would think that it would be killed almost instantly if that was the
> case. It runs for like 20 to 30 minutes before it is killed.
>
> I don't background any of these processes and the taskvent process runs for
> a long time before I get the command prompt back even when it completes all
> of the jobs with a smaller message. And the the ~93% of memory usage (using
> UNIX "top" command) is very consistent until it is killed. So I don't think
> that is the problem.
>
> Here is another possibility for you to consider. We are constructing a new
> message in the Ventilator in each cycle inside the loop:
>
> for (task_nbr = 0; task_nbr < numberOfJobs; task_nbr++) {
>
>                 // Stuff a character array with a bunch of AAAAA
>                 // characters of quantity based on messageSize
>                 unsigned char *p = (unsigned char *) malloc(
>                                 messageSize * sizeof(unsigned char));
>                 memset((void *) p, 'A', messageSize);
>                 p[messageSize - 1] = '\0';
>
>                 // Send the message and reclaim memory
>                 s_send(sender, p);
>                 free(p);
>         }
>
> Notice that the last two lines of code, I am sending the message and
> immediately calling "free()" after sending. Do you think it is possible that
> the memory is being freed too soon before the message completes sending?
>
> In the meantime, I am going to run this in a debugger to see where it is
> actually crashing.
>
> Mark
> On Friday, April 11, 2014 12:29 AM, Pieter Hintjens <ph at imatix.com> wrote:
> Mark,
>
>> 3. In window #3:  ./taskvent 5000 23000000    (jobs, messageSize in bytes)
>> After a
>> while, prior to completion, window #3 (taskvent) will display the word
>> "Killed" and the process will stop without further action.
>
> Perhaps it's consuming too much memory for a single process and then
> being killed by the OS?
>
> 5000 x 2.3 MB = 11 500 MB.
>
>
> -Pieter
>
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